Communication systems today, such as Motorola's “iDEN” system, provide users with so-called dispatch services. Unlike the interconnect services provided by today's cellular systems, dispatch services have been traditionally provided by two-way radio systems. Such services allow a user to communicate in ways that are difficult or costly using today's cellular systems. The dispatch group call service, for example, enables a user to communicate with a group of people simultaneously and instantaneously, usually just by depressing a push-to-talk (PTT) button. Using a cellular system, such a call could not occur instantaneously since either telephone numbers would need to be dialed for a three-way call or arrangements would need to be made to setup a conference call.
Likewise, the dispatch individual call service enables a user to communicate with another user quickly and spontaneously. This feature is ideal for two people who are working together but are unable to speak with one another directly such as two people working in concert but in different parts of a building. Where a wireless telephone call is more appropriate for a conversation, short messages between two people as they work are better facilitated by the dispatch individual call service.
Both of these dispatch services are made more flexible by a so-called dispatch scan service that allows a user to scan for call activity across multiple dispatch groups. For example, a user involved in a dispatch group or individual call can simultaneously scan for any call activity occurring among members of a different dispatch group and join such a call while in-progress. Thus, a user, such as a supervisor, can effectively monitor a number of different dispatch groups and take part in their calls as required.
Although these dispatch services are available to users of Motorola's “iDEN” system, they are not available on today's CDMA systems. The co-pending application “METHOD AND APPARATUS FOR PROVIDING DISPATCH SERVICE IN A CDMA COMMUNICATION SYSTEM” discloses modifications to the IS-95 CDMA standard to allow the members of a dispatch group to decode the group communication. For example, the CDMA long-code mask used to encode the communication is generated using a dispatch identifier instead of the Electronic Serial Number (ESN). Also, a dispatch identifier is used to determine the appropriate paging resource for transmitting and receiving dispatch call pages. However, this co-pending application does not disclose a CDMA embodiment that enables the dispatch scan service. Therefore, a need exists for an apparatus and method for providing a dispatch scan service on a CDMA communication system.